Investigating the no. of moles of water of crystallization, in one mole of hydrated ethanedioic acid.

2. You now have to make up 250 cm³ of a solution made from the ethanedioic acid, and the 1.5 g of acid weighed out. First you put 50 ml of distilled water into a beaker, and then you add the 1.5 g of acid, and dissolve it whilst stirring with a glass rod. When dissolved, you then put this solution into a conical flask, and make the solution up to 250 cm³, adding distilled water. When you have the 250 cm³ of a solution, you put it into a volumetric flask, using a filter funnel.

3. Rinse a 25 cm³ pipette with this solution, then pipette 25 cm³ of the solution using pipette filler, into a conical flask.

4. You then measure 20 cm³ of 1.0 mol dm ³ sulphuric acid using a measuring cylinder, and add it to the solution in the conical flask.

5. Fill a burette to the tip using a filter funnel with potassium manganate (VII).

6. Now you heat the solution on a tripod, using a Bunsen burner. You do this, till the temperature reaches between 65-70°C. Measure the temperature using a thermometer.

7. When it reaches the specified temperature, quickly remove the conical flask onto the white tile situated under the burette containing the potassium manganate (VII), and titrate this solution.

8. Titrate the solution till it reaches a pale pink colour.

9. You now repeat the steps 3-8 at least three times, to get a fair result.

Safety

During the experiment, some safety regulations were carried out. Safety goggles were worn throughout the experiment, hands were washed after contact with chemicals and long hair was tied back. If ethanedioic acid gets on your hands, it can be dangerous if your hands then get in contact with your eyes, or mouth. Also the Bunsen burner was kept on a yellow flame, when it wasn't in use.

Fair Test

To make it fair, I had to make sure, that exactly 1.5 g of ethanedioic acid was used weighed at the beginning of the experiment. Also the amount of sulphuric acid (20 cm³), had to be measured precisely. Both the burette and the pipette had to be rinsed. The burette with potassium manganate (VII), and the pipette with the ethanedioic acid. Also different conical flasks were used each time. When I did the experiment, I made sure the solution was at the same temperature each time, 65°C, as it could have a significant factor on my results.

This is a table of the results:

Conclusion:

The experiment was done, to find the amount of water in hydrated ethanedioic acid, H C O · H O. Using the information found, I will now work out the number of moles, water crystallization, there is present in one mole of hydrated ethanedioic acid.

The ionic equation is:

2MnO ¯ + 16H + 5C O ² 2Mn² + 8H O + 10CO

Using the formula:

CaVa = Na

CbVb Nb

Which refers to, Hydrated ethanedioic acid

Potassium manganate (VII)

Using the formula above, means that the concentration of hydrated ethanedioic acid would be:

X 0.025 = 5

0.02 x 0.0232 2

So, x 0.025 = 2.5

0.00464

Then, x 0.025 = 2.5 x 0.02 x 0.0232

= 0.00116

= 0.00116

0.025

= 0.0464 dm³ of C O

Now we know the concentration, we can find the amount:

n = cV

= 0.0464 x 0.25

= 0.0116 mols

The overall Mr of H C O · H O is:

Mr = m

n

Mr = 1.5 1.5

0.0116

= 129.31

129.31 = Mr of H C O + H O

129.31 = 90 + 18

So the number of moles of H O is:

= (129.31-90)

18

= 2.2

The number of moles of water of crystallization present in H C O · H O is 2, as I've rounded it down, because its under 0.4 whereas if it was 0.5 I would have rounded it up to the next whole number.

Overall equation: H C O · 2H O

Deyar Yasin